# CVE-2026-13048: Data::MuForm::Localizer versions through 0.05 for Perl execute Perl from a message catalog header, reached at an arbitrary path because load

> Attackers can execute arbitrary Perl code by manipulating the language attribute to load a malicious message catalog file.

- **Severity:** High 8.2 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 13 Aug 2026
- **Updated:** 14 Aug 2026
- **Also known as:** GHSA-9pqq-8968-ccrw

## What is CVE-2026-13048?

CVE-2026-13048 is a high-severity code injection vulnerability, published on 13 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Data::MuForm::Localizer versions through 0.05 for Perl execute Perl from a message catalog header, reached at an arbitrary path because load_lexicon interpolates the language attribute into the catalog filename.

load_lexicon builds the catalog path by appending `Messages/$lang.po` to the directory holding Localizer.pm, where $lang is the language attribute, with no check that it names a bare locale tag. A value holding `../` segments walks out of the message directory, so any readable path with a `.po` suffix is loaded. While parsing the catalog, extract_header_msgstr takes the `Plural-Forms:` header, prefixes `$` to the bare words nplurals, plural and n, and passes the rest verbatim into a string that is evaluated: the nplurals form evaluates the header expression immediately, and the plural_code form compiles it into a subroutine whose body runs when a plural message is localized. A header of `nplurals=2; plural=(system('...'),0);` therefore runs that command as the catalog loads. The evaluation inherits strict, so an expression that assigns to an undeclared variable fails to compile, while one built from calls alone does not.

An application that sets the language attribute from request data, an Accept-Language header or a locale parameter, and an attacker who can place a file with a `.po` suffix and chosen contents at a readable path, together give code execution as the application user. The message expansion path is not affected: expand_named substitutes only the placeholder names the caller supplies, and _mangle_value returns the value unchanged.

Weakness: CWE-95 (Improper Neutralization of Directives in Dynamically Evaluated Code), CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)

## Which versions are affected by CVE-2026-13048?


## How do I fix CVE-2026-13048?

No fix has been published for CVE-2026-13048 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-13048 being exploited?

There is no known exploitation of CVE-2026-13048 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-13048 and fix it if it is affected.

What it is: CVE-2026-13048 is a high-severity code injection vulnerability, published on 13 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-13048 in the wild and no public exploit code.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-13048/ (Markdown: https://insights.sbomify.com/CVE-2026-13048/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-13048
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-13048
- OSV: https://osv.dev/vulnerability/CVE-2026-13048

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-13048/
Summaries are generated and may contain mistakes; the official description above is the record.